Apparatus used to make beverages from a solid component and a liquid component for distributing directly to the consumer are legion in number. One example is a machine which meters a predetermined amount of powder and water to a mixing area. Another example is combination coffee grinders and brewers that are finding great acceptance from restaurants and the like. Brewing coffee directly from freshly ground beans in the same apparatus has considerable appeal. A typical combination grinding and brewing apparatus employs a hopper which upon a signal discharges beans into a proportioning device which measures the desired quantity of beans. The beans are then transferred to a grinder that grinds the beans to a desired consistency after which the ground coffee is delivered to a filter within the brewing basked immediately before hot water is sprayed over the grounds. A common feature in most apparatus of this type is the use of a sealing structure which prevents moisture emanating from the hot water tank and brewing basket from reaching the interior of the grinder assembly. Wetting of the grounds prior to reaching the brewing basket is undesirable, particularly when the grounds are still in the grinder itself. It causes problems with the proper distribution of the ground coffee to the brew basket and is difficult to clean.
A number of structures have been devised to prevent the egress of unwanted moisture into the grinder. An example may be found in U.S. Pat. No. 4,913,037 issued to Brian D. Newnan and assigned to the same assignee as the present invention. In the patent, the passage between the grinder and the brew basket is conveniently sealed by a solenoid operated valve which is open during the grinding operation but closes when the grinder motor shuts down. The valve is a flap of material which is pivotally mounted, biased into a closed position and responsive to the movement of a solenoid plunger for opening the passageway. The valve can also be manually opened by use of a finger tab thus allowing access into the passageway for cleaning when required. The passageway itself is defined by an elbow shaped hood which serves to guide the coffee grounds when ejected from the grinder through the valve opening into the brew basket.
The prior art device mentioned above does not meet the basic requirements of combination grinder brewers in which space is severely restricted. For example, the pivoting action of the prior art valve and the linkage to the solenoid plunger require valuable space as does the passageway defined by the elbow shaped hood. Additionally, it is desirable to have an apparatus having a valve assembly in which the moisture of the brewing operation could be sealed off during the brewing cycle without the sacrifice of valuable space while simultaneously maintaining good coffee ground dispersal across the filter paper within the brew basket. Additionally, the valve assembly should allow for easy manual access into the valve interior for cleaning and maintenance. Such an apparatus is described in the aforementioned U.S. application Ser. No. 07/951,449 which provides for a coffee grinding and brewing apparatus in which the passageway communicating with the grinder and brewing area is selectively opened when the grinder motor is activated and closed when not. Thus, moisture emanating from the brewing cycle cannot reach the grinder as the passageway therebetween is sealed shut. A slide plate or shutter having an opening is directly connected to a solenoid by a solenoid plunger. When the grinder is activated, the solenoid is activated and moves the shutter into an open position in which the opening of the shutter is in registry with the opening of the grinder head. The movement of the solenoid plunger and plate are essentially coplanar which reduces the number of working and moving parts. Moreover, the shutter is provided with a tab finger which extends into the brewing area a sufficient distance to deflect at least a portion of the stream of coffee grounds ejected from the grinder thereby ensuring the coffee grounds are properly distributed prior to brewing. The timing of operation sequence is such that the solenoid valve remains operational for a predetermined time period after the grinder cease operation. Once the predetermined time period has elapsed, the solenoid shuts off and a biasing element closes the shutter just prior to the brewing cycle so that moisture therefrom does not proceed into the grinding head.
While the above valve operates as intended, it has been noted, that after operation of the apparatus over an extended period of time, a residue builds up on the surfaces exposed to the moisture emanating from the solid and liquid mixing side, e.g., the brewer. The residue comes from certain soluble compounds that are carried by the moisture and are left on the exposed surfaces due to evaporation. The film contaminant is often sticky causing the moving surfaces to fuse together, making it nearly impossible to operate the device. One solution is to provide a larger solenoid to move the slide valve. While the finger tab does provide one way to move apart the fused surfaces, it does require frequent attention which may not be practical in most operating environments.